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Date:   Thu, 31 Mar 2022 10:57:53 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     David Hildenbrand <david@redhat.com>
Cc:     Christoph Hellwig <hch@lst.de>, Alex Sierra <alex.sierra@amd.com>,
        jgg@nvidia.com, Felix.Kuehling@amd.com, linux-mm@kvack.org,
        rcampbell@nvidia.com, linux-ext4@vger.kernel.org,
        linux-xfs@vger.kernel.org, amd-gfx@lists.freedesktop.org,
        dri-devel@lists.freedesktop.org, jglisse@redhat.com,
        apopple@nvidia.com, willy@infradead.org, akpm@linux-foundation.org
Subject: Re: [PATCH v2 1/3] mm: add vm_normal_lru_pages for LRU handled
 pages only
Message-ID: <20220331085753.GA22487@lst.de>
References: <20220330212537.12186-1-alex.sierra@amd.com> <20220330212537.12186-2-alex.sierra@amd.com> <20220331085341.GA22102@lst.de> <709b459a-3c71-49b1-7ac1-3144ae0fa89a@redhat.com>
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On Thu, Mar 31, 2022 at 10:55:13AM +0200, David Hildenbrand wrote:
> > Why can't this deal with ZONE_DEVICE pages?  It certainly has
> > nothing do with a LRU I think.  In fact being able to have
> > stats that count say the number of device pages here would
> > probably be useful at some point.
> > 
> > In general I find the vm_normal_lru_page vs vm_normal_page
> > API highly confusing.  An explicit check for zone device pages
> > in the dozen or so spots that care has a much better documentation
> > value, especially if accompanied by comments where it isn't entirely
> > obvious.
> 
> What's your thought on FOLL_LRU?

Also a bit confusing, but inbetween all these FOLL_ flags it doesn't
really matter any more.